Determination of honey adulteration by adding different rations of corn syrup using FTIR-ATR spectroscopy

Difficulty in production and high price make the supply of fake and adulterated honey to the market increasingly widespread. While adulterated honey causes unfair competition in terms of honey producers and the honey sector, it also negatively effects the consumer both economically and in terms of health. The methods used to determine honey quality are expensive and time consuming, requiring many chemicals. Therefore, it is not possible to quickly detect fraudulent honey in the sector. The methods used to determine honey quality are expensive and time consuming, requiring many chemicals. Therefore, it is not possible to quickly detect fraudulent honey in the industry. Since commercial corn syrup is often adulterated by adding commercial corn syrup to honey, 3 types of commercial corn syrups (High Fructose syrup, Glucose-Fructose syrup and Maltose syrup) with different properties obtained from the food industry were used as adulteration agent in this study. 72 pure honey samples were obtained directly from honey producers or honey producer associations. Moisture content, Brix, pH, free acidity, colour and sugar analysis were applied to pure honey samples and the results were found to be in accordance with the TGK Honey Standard. In order to determine the adulteration in honey using Fourier Transform Infrared (FTIR) Spectroscopy, three different corn syrups were added to the pure honey samples at different rates (10-20-30-40-50-70%). Pure and adulterated honey samples were scanned in the range of 4000-525 cm-1 wavenumbers in FTIR-ATR spectroscopy. The absorbance values obtained in the spectral band range of 1500-750 cm-1, which is the fingerprint region where the properties of carbohydrates are better observed, were used in chemometric methods. The FTIR data were evaluated by Principal Component Analysis (PCA), Least Squares-Discriminant Analysis (PLS-DA) and Least Squares Regression Analysis (PLS-R). Pure and adulterated honey samples were classified with the PCA model, and PC1 and PC2 (first two main components) could explain 87.8% of the total variance. According to the PLS-DA results, 100% sensitivity, specificity, model efficiency and correct classification rate were obtained in the classification of pure and commercial corn syrups added to honeys. With the developed PCA and PLS-DA models, the separation and classification of pure honey and adulterated honey samples were successfully accomplished. In the PLS-R analysis, adulteration rates could be determined quantitatively. RMSEC and RMSEP values of PLS-R models were determined for High fructose syrup, Glucose-fructose syrup and Maltose syrup as 2.53 and 2.93%, 2.75% and 3.03%, 3.28 and 2.91%, respectively. Also high correlation coefficients (R2> 0.981) were obtained for all syrups. PLS-R analysis were applied to glucose and fructose contents of honey samples determined by HPLC and FTIR data. As a result, high correlation (R2> 0.925) was obtained. RMSEC and RMSEP values of fructose content were found to be 1.30% and 0.97, and glucose contents were found to be 1.16% and 1.04%, respectively. In the established model, the purity of 72 pure honey samples collected from the producers was estimated between 92-112%, while the estimated error value was determined as 4.24%. As a result of the use of FTIR-ATR spectroscopy in combination with chemometric methods, adulterated honey samples can be distinguished from pure honeys, and honeys adulterated with different corn syrup can be classified separately. The ratios of sugar syrup added to honey could also be analyzed quantitatively.